1. Field of the Invention
The present invention relates to an image pickup apparatus including an image pickup element, such as a charge-coupled device (CCD) image sensor or a complementary metal-oxide semiconductor (CMOS) image sensor, and to a control method for the image pickup apparatus. More particularly, the present invention relates to processing for correcting data output from pixels of the image pickup element.
2. Description of the Related Art
Defective pixels may be generated in image pickup elements provided in image pickup apparatuses, such as digital cameras or video cameras, in the process of manufacture or the like. The levels of outputs from defective pixels are different from the levels of outputs from normal pixels, and such differences cause deteriorations in image quality.
A technique for performing correction of a defective pixel of an image pickup element, data of the defective pixel having been stored in advance, and performing, if necessary, processing for inspecting the image pickup element, extracting data corresponding to a defective pixel that generates an output at a level different from those of other pixels, storing data of the extracted defective pixel, and performing correction for the defective pixel is disclosed, for example, in Japanese Patent Laid-Open No. 2002-125154.
In addition, a technique for performing real-time correction for a defective pixel by extracting data corresponding to a defective pixel on the basis of a difference between the signal level of a specific pixel having a specific color and the signal level of an adjacent pixel having the specific color in a captured image and on the basis of a difference in the signal level of a peripheral pixel having a different color and the signal level of another peripheral pixel having the different color is disclosed, for example, in Japanese Patent Laid-Open No. 06-30425.
In rare instances, apart from a signal of a defective pixel, due to the influence of cosmic rays, extraneous noise, or the like, a non-reproducible signal being an output at a level higher than those of other pixels, having a continuity with respect to an adjacent pixel, irrespective of the color of the pixel, and appearing as sudden noise may be generated.
With the configuration described in Japanese Patent Laid-Open No. 2002-125154, even in a case where it is desired to perform correction for a pixel outputting such a non-reproducible signal, correction can be performed only for a defective pixel whose data has been stored in advance.
In addition, with the configuration described in Japanese Patent Laid-Open No. 6-30425, in the case that a defective pixel is identified simply on the basis of a difference in signal level between pixels having the same color, data corresponding to a pixel to be subjected to correction may not be properly extracted.
In addition, since extraction of data corresponding to and correction of a defective pixel are performed in accordance with a specific threshold determination based on a difference in signal level between pixels having the same color, a high-frequency component, such as an object edge, may be falsely detected.